Frames can be classified by style, and are available in numerous material combinations:
- Lenses are completely enclosed by the frame eye wire.
- only a portion (usually 1/2) of the lenses are encircled by the frame eye wire.
Virtually no portion of the lenses are enclosed by the frame eye wire. These are often referred to as "drill mount" frames because the frame chassis is held together by drilling a hole in the lenses and secured with screws or pressure fasteners.